A conventional adjustable wrench is disclosed in FIGS. 6 and 7, and generally includes a handle 50 and a head 51 integrally connected to an end of the handle 50. A fixed jaw 52 extends from the head 51 and a groove 53 is defined in the head 51. A through hole 54 is defined through the head 51 and located parallel to and in communication with the groove 53. A recess 55 is defined radially and in communication with the through hole 54 and extends into the fixed jaw 52 so as to form a space 550 for receiving the flange 62 of a movable jaw 60 which will be described hereinafter. The movable jaw 60 includes a rack piece 61 and a flange 62 extends from the rack piece 61 and connected to a root of the movable jaw 60. The rack piece 61 is movably inserted in the groove 53 and the through hole 54 and a thumb screw 70 is rotatably connected to the head 51 and engaged with the rack piece 61 so that the movable jaw 60 moves toward or away from the fixed jaw 52 by rotating the thumb screw 70. The recess 55 and the space 550 in the fixed jaw 52 receive the flange 62 on the movable jaw 60 when the movable jaw 60 is matched with the fixed jaw 52. The fixed jaw 52 experiences significant pressure during use and experience has shown the fixed jaw 52 tends to be broken at the root portion thereof after a period of use of the wrench. The damage to the fixed jaw 52 results from that the recess 55 and the space 550 which weakens the structural strength of the fixed jaw 52. Besides, the recess 55 and the space 550 require a lot of machining.
The present invention intends to provide an adjustable wrench wherein there is no recess as shown in the conventional wrench and the through hole only makes a circular hole in an outer surface of the head. The flange on the movable jaw is shorter than that of the conventional one so that the fixed jaw needs not to be machined a recess and the structural strength of the fixed jaw is reinforced.